This disclosure generally relates to assembly lines for vehicles and more specifically error-proofing systems thereof. Many automotive assembly plants include error proofing (in Japanese, “pokayoke”) systems to maintain quality control as vehicles are assembled on an assembly line. Pokayoke systems typically include controllers stationed at each station of the assembly line, which are used to detect if a process was performed according to predefined standards or thresholds. For example, an assembly process can include a procedure to tighten joints on a vehicle (such as a nut/bolt joint) using an electric or pneumatic nutrunner. During such an assembly process, it is possible that a joint will fail to be tightened at the proper torque or will be tightened at an incorrect angle, which can lead to a cross threaded joint.
Pokayoke controllers are often used to alert users to the existence of these kinds of assembly faults or abnormalities, such as by flashing a light or sounding an alarm, or by causing the assembly line to halt. When this happens, a supervisor is typically called to correct the abnormality. However, there may not be time to correct the abnormality immediately, and so the supervisor will often bypass the pokayoke system by overriding the alarm and restarting the assembly line, intending to repair the vehicle at some point farther down the assembly line.
It is incumbent upon the supervisor issuing the bypass to ensure that the abnormality is eventually corrected. The supervisor must therefore manually keep track of bypassed vehicles throughout the assembly process. However, it is difficult and time consuming for users to accurately record each vehicle and the needed repairs and to later remember all the information necessary to conduct the repair. Therefore, abnormalities in bypassed vehicles are often not tracked effectively and therefore are often not adequately repaired. In addition, because repairs are performed after the vehicle has moved down the assembly line, the tools needed for the repairs are manual tools that are not connected to the pokayoke system.
It has been observed that users tasked with correcting abnormalities such as those described above have been known to: (i) repair the wrong joint, (ii) repair the correct joint on the wrong vehicle, (iii) use an incorrect torque when repairing the joint, (iv) forget to repair the abnormality altogether, and/or (v) fail to log a repair as completed. Thus, due to manual repair tracking, an incorrectly installed joint can remain present after the vehicle is released down the assembly line. Sometimes, even new abnormalities are introduced during the repair process. Additionally, a user may complete a repair but forget to log the repair, negatively impacting traceability and quality control.